000001586 001__ 1586
000001586 005__ 20190801105607.0
000001586 037__ $$aBELLE2-MTHESIS-2019-004
000001586 041__ $$aeng
000001586 100__ $$aLex Greeven
000001586 245__ $$aExclusive untagged analysis of the semi-leptonic decay B→ρlν in preparation for extracting |V_ub| using early Belle II data
000001586 260__ $$aBonn$$bPhysikalisches Institut$$c2019
000001586 300__ $$a129
000001586 500__ $$aPresented on 01 08 2019
000001586 502__ $$aMSc$$bBonn, University of Bonn$$c2019
000001586 520__ $$aIn this thesis, the decay B → ρlν was studied using Belle II Monte Carlo simulation corresponding to the early Belle II data size of 6.5 fb−1. Selections were performed to reduce background events, and BDTs were trained to further reject continuum and BB background events. It was found that performing a FOM selection on the BDT output classifiers lead to highly correlated signal and background shapes in ∆E and M_bc, so instead the BDT output classifiers were fitted. It was found that a significant branching fraction measurement was not possible with the current data set, and at least 16 fb−1 is required for the ‘evidence’ of B → ρlν at Belle II. Due to time limitations, further study on the systematic uncertainties of this analysis could not be performed, but the major sources are expected to be the MC modeling of the detector response,the MC modeling of continuum, and the modeling of inclusive Xu background. Early Belle II data showed disagreements compared to the MC that was used, indicating that further studies by the Belle II detector groups are required to fully understand the data before a meaningful signal extraction on data is possible performed.
000001586 700__ $$aProf. Dr. Jochen Dingfelder$$edir.
000001586 700__ $$aDr. Peter Lewis$$edir.
000001586 8560_ $$flex.marinus.greeven@desy.de
000001586 8564_ $$uhttps://docs.belle2.org/record/1586/files/BELLE2-MTHESIS-2019-004.pdf
000001586 980__ $$aTHESIS